This is Mrs Beeton’s blackcurrant jam recipe, published in her Book of Household Management in 1907.
Note: this recipe is provided for information only, I have not tested it yet. Once I do, I will add a recipe card.
Original recipe

2510.—BLACK CURRANT JAM.
Ingredients.—To each lb. of fruit allow 1 lb. of loaf sugar, and ¼ of a pint of water.
Method.—Remove the fruit, which should be ripe and perfectly dry, from the stalks, put it into a preserving-pan with the water, bring to boiling point, and simmer gently for 20 minutes. Add the sugar, and boil for about ½ an hour from the time the jam re-boils, or until a little almost immediately sets when tested on a cold plate. Towards the end of the process the jam must be stirred almost continuously, to prevent it boiling over or sticking to the bottom of the pan. Pour into pots, at once cover closely, and store in a cool, dry place.
Time.—From 50 to 60 minutes. Average Cost, 4d. or 5d. per lb.